Do bioflavonoids enhance Vitamin C absorption?

Vitamin C absorption from the gut is governed by sodium content for active transport. For passive absorption throughout the length of the intestine the vitamin does not use a similar co-factor.

The bioflavonoids come into play after vitamin C has been absorbed and is in circulation.  This vitamin has a relatively short half-life and depends on other antioxidants to act as electron donors to 'reduce' oxidized vitamin C (dehydroascorbate) back into the antioxidant form (ascorbate; ascorbic acid).  Various antioxidants, including bioflavonoids and polyphenols in fruits, are typically used to provide that extra benefit.  So the recycling and longevity of vitamin C after absorption depends greatly on the presence of other antioxidants; including not only rutin and bioflavonoids but also alpha lipoic acid, glutathione, and numerous other antioxidants.

So there is a benefit to using a base, often called vitamin C complex, in a vitamin C formula, but not so much in the initial absorption as in the vitamin's retention and recycling for re-use over time.  The variety of antioxidant-related nutrients in the human diet is thought responsible for why humans can retain vitamin C between meals when we cannot manufacture our own from blood sugar at will, as most mammals can.

Does zinc supplementation reduce absorption of calcium or magnesium?

In general, no.  While it’s true that zinc can reduce absorption of calcium it would have to be a high level to do so; studies showing such a relationship have primarily been on zinc sulfate supplements containing about 140 mg of elemental zinc.  This is far above the RDA/DV level of 15 mg. typically found in dietary supplements, or even the 30-50 mg. found in some immune or prostate formulas.  One typical study used 142 mg/day of zinc to achieve this; far higher than the amount in supplement formulas.  The study noted that the decrease in calcium absorption occurred when low calcium and high zinc intake was noted, but not with adequate calcium intake, and specifically tested lower doses of zinc along with low calcium intake and did not find a reduced absorption of calcium at commonly supplemented levels:  https://www.ncbi.nlm.nih.gov/pubmed/1452955

 

So the issue is limited to a very high zinc intake combined with a very low calcium intake, not the levels found in common supplements.  One will find zinc and calcium together in multiple vitamins or some mineral formulas, but at typically available levels they are not shown to cause the reduced absorption of calcium found in those studies cited above. 

 

The issue has also been studied for magnesium versus zinc intake.  Likewise, very high zinc intake interfered with low calcium intake (500 mg.) but less likely at higher levels of calcium intake.  Again, the levels of zinc in question (around 140 mg.) are not typically found in over-the-counter zinc supplements or multivitamins. https://www.ncbi.nlm.nih.gov/pubmed/7836627/ 

 

 It is more convenient for people to supplement with combination formulations instead of taking several single ingredient supplements, typically increasing compliance with label instructions and dosing.  Knowing that it's okay to take minerals in combinations that are commonly found in the marketplace is reassuring when some pundits claim that it is inappropriate based on the unusual circumstances of low mineral intake combined with abnormally high zinc intake.  For physicians prescribing the high strength zinc products, this is something to consider, but not something for consumers of dietary supplement formulas to be concerned about.

Neil was interviewed about CoQ10 for a trade magazine

* How would you rate consumer awareness of the health benefits of CoQ10? Neil: There is actually a fair amount of consistently positive press on CoEnzyme Q10 (CoQ10), with a significant part of that because of this antioxidant nutrient’s role in cardiovascular and heart health. Many cardiologists recommend CoQ10 to their patients and popular books, such as by Dr. Sinatra, promote the healthful effects of CoQ10 to at-risk people. I would go so far as to suggest that CoQ10 has picked up some of the wide popularity as a heart nutrient that vitamin E had several years ago (but lost due to consumer confusion caused by unwarranted negative publicity). The fact that CoQ10 is so obviously safe, versatile, and useful has propelled it to a high place on the list of cardiovascular nutrients. * What is driving consumer interest in CoQ10 products? Neil: The multiple roles of CoQ10 in the human body make it uniquely useful in protecting cells and energizing essential processes such as heart action and immunity. Energy supports the constant pumping of the heart muscle, but also supports immune functions and antioxidant activity. Lack of energy is a common complaint heard by doctors, and active people need good sources of energy, so nutrients that promise to improve the energetics of the body are always in demand. In addition, new technologies to improve the historically poor absorption of CoQ10 have expanded the product category as prices have moderated, which is a perfect place for people selling CoQ10 to be in. Tell us more about CoQ10: Neil: Ubiquinol doubles as an antioxidant, and like other antioxidants the body can convert from one to the other and back again. Although Ubiquinol lacks much in the way of human clinical trials, supplemental Ubiquinone mostly converts to Ubiquinol during transport from the gut to the circulatory system. Ubiquinol is the primary form of the nutrient that circulates in the body. Ubiquinol converts to Ubiquinone to stimulate the production of cellular energy. CoQ10 is a fat-soluble nutrient and therefore should only be taken with meals containing significant amounts of fat. That has traditionally been the main limiting factor in absorption. Blending CoQ10 into an oily base to make softgel capsules is somewhat superior to dry capsules because a little oil is provided, but again there just isn’t enough oil in a capsule to make a big difference when the nutrient is not dissolved into the oil. When CoQ10 is completely dissolved into an oil, forming a crystal-free solution, it does make it several times more absorbable. But all oily solvents are not created equal! Some manufacturers use the synthetic chemical polysorbate 80 as the base and main ingredient in the softgel capsule, whereas others use only natural citrus or coconut oil fractions to do the same job because we prefer to have natural bases.